Automatic telephone system.



S. B. WILLIAMS, JR

AUTOMATIC TELEPHONE SYSTEM. APPLICATION FILED my. 31, 1916.

Patented Nov. 2?, 19 17.,

3 SHEETSSHEET 1.

7 65 H van for:

S. B. WILLIAMS, In.

' AUTOMATIC TELEPHONE SYSTEM.

APPLICATION min JAN.3I.19I6.

' 11. ,VQMWWT Eatented Nov. 27, 191?.

3 SHEETSSHEET 2- L //1 yen for." Jamue/ B M lTl/mmfi Jk VM KMLM -f S. B. WILLIAMS, JR. AUTOMATIC TELEPHONE SYSTEM,

APPLICATION FILED JAN. 3|. l9l6.

1 @3570 Patentad N0v..27,1917.

3 SHEETSSHEET 3.

l6 ti 47017 i L23, 6,I4,|6.

TTNTTED STATES PAEN SAMUEL .B. WILLIAMS, JR., 013 BROOKLYN, NEW YORK, ASSIGNOR TO WESTERN ELEC TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE SYSTEM.

Application. filed Janua y 3 1.916.

To all whom it may concern:

Be it known that I, SAMUEL B. WILL A u's, J r., a citizen of the United States, reslding at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Automatic Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone systems and particularly to systems of the type in which switching apparatus at the central ofiice acts automatically to find and make connection with a calling subscribers line.

In systems of the type toward wh ch the present invention is particularly d rected, a number of line finding and connecting circuits are provided for the common use of .a larger number of telephone lines, and when any one of the telephone lines initiates a call, one or another of the line finding switches in which the finder circuits terminate is automatically made operative to connect with the calling line, the finder switch that is made operative being one that is at the time disengaged or idle. The prmclpal object of this invention is to provide an 1mproved control system for use in such an organization to insure one finder circuit, and one only, being made operative to connect with a calling line when a callis initiated; to prevent the finder circuit that is thus made operative from establishing connection with more than one line; and to simplify and improve the part of the organization which has to do with the preparing or assigning of the finder circuits and switches for serving the calling line.

The novel features of the invention through the provision of which the above mentioned and other advantageous results are attained, will be explained by reference to the accompanying drawings, in which a preferred embodiment of the invention is shown, and in which Figures 1,2and3 taken together, and with Fig. l at the left and Fig. 3 at the right of Fig. 2, illustrate the circuit organization employed in this particular embodiment.

In the organization illustrated, four Inctallic circuit telephone lines are shown extending from subscribers stations A, A B, and B to the central office where they erminate upon stationery contact terminals Specification of Letters Patent.

Patented Nov. 27, 1917.

Se ial No. 75,328.

of two line finder switches C and D. Each line has connection at the central ofiice through the resting contacts of a cut-off relay 11 with the windings of a line relay 12 between which is bridged a battery 18.

The lines are divided into groups at the central ofiice, the lines from stations A and A being two of a number of lines that are assumed to constitute group A, and the lines from stations B and B being assumed to be two of a number of lines that are assumed to constitute group G. Groups A and B may be two of a number of groups of lines that are served by the finder switches C' and D, such other groups being-arranged similarly to the two groups that are shown.

Each group of lines has associated with it certain group apparatus, consisting in the present instance of relays 19 and 24 and a sequence switch 100. This group apparatus is under the control of the line relays of the corresponding group of subscribers lines,

and through the medium of the starting (11'- cuit apparatus E, common to all of the groups, controls the starting of one of the line finders to find calling line, and also through the medium of the trip magnets 16 and 17, common to all of the line finder switches, controls a preliminary group selection by whichever line finder that is started.

The finder switches C and D are two of a larger number which may be provided for serving all of the lines of the various groups,

such additional finder switches being sin'iilu r to those which are shown. Each of the finder switches serves as the connecting member at one end of an associated lludcr circuit, C, D, the other end of which may be provided with a cord selector through the medium of which an idle connecting cord circuit may be selected to extend the circuit of a calling line to that of :1 called line. The cord selectors and connecting cord circuits, which may be assumed to be of any suitable and wellknown type, are not shown as they form no part of the present invention. I

As the finder switches in themselves are not novel, they are shown merely diagrammatically. These switches may be substantially like the switch illustrated and described in patent to James L. McQuarrie No. 1,177,0l, issued March 28, 1916,

The organization involves the use of sequence switches, which are shown diagrammatically and; may be of the type disclosed in Patent, 1,127,808, issued February 9, 1915, to Reynolds and Baldwin. The electromagnetically controlled motor or driving mechanism or these switches is indicated diagrammatically in the parts designated and 200 in the drawings, and the as sociated switch contacts'ar'e" designated 101' to 103 inclusive, in the case of sequence switches 100, and 201' to 218'inclusive, i11 the case of sequence switches" 200. The numerals applied to the sequence switch contacts 101 and 201, indicate the only positions of each switch in which the associated contacts are open; the numerals applied to the other contacts of each switch, indicate the position of each switch in which the associated contacts are closed. 7

The commutators of the line finder switches are shown at the tops of their re spective switches in Fig. 2 of the drawing. Instead of showing the circuit connections with such of these commutator segments as are involved in the present disclosure, such circuit connections are merely indicated by correspondingly lettered squares on Fig, 3 of the drawing.

The organization disclosed will be best presented, it is believed, by proceeding directly to a description of the operation of the system.

When one or the subscribers, say the subscriber at station A, takes his telephone from his hook, his line relay 12 is energized and closes its contact. This establishes a path to ground from conductor 18, which is multiply connected to the armatures of all of the line relays in the group which it serves. If it be assumed that the sequence switch 100 of the group A in which the line from station A terminates is in its normal or 5 first position, the grounding of the conductor 18 completes an energizing circuit for the group relay 19 by way of sequence switch contacts 103 closed in positions 18?; to'lior the switch. Relay 19' thereupon closes its contact 21 and assuming that the starting circuit relays 22 and 23 are inert, completes a circuit for the energization of the group relay 24, this circuit includin'g the righthand winding of relay 24, contact 21 of relay 19, resting contact 25 of relay 22 and resting contact 26 of relay 23. Relay 24 thereupon operates and closes its contacts 27 and 28. The closure of the contacts 27 completes a circuit that includes the lefthand winding of the relay 24 and the winding of the line finder trip magnet 16 in par alle'l branches, and the winding of the starting relay.22 in the common portion or the circuit. The energization of the trip magnet 16 sets the tripping mechanism of all of the line finders to tripthe corresponding set of brushes of whiche er' line finder is started, and thus to efi'ect the preliminary selection of the group of lines in which the calling line is located. The energization of the left-hand winding of group relay 24 serves to lock up this relay independently of the circuit of the right-hand winding; and the energization of starting relay 22, by breaking the resting contact 25, interrupts the path'over which the initial energization of group relay 24 by way or its right-hand winding was first efiected,-andstarts a finder switch in a manner hereinafter to be dcscribed.

The closur'e'of contacts 280i group relay 24' effected in the initial energization of the relay, completes the circuits or the motor magnet of sequence switch 1'00by way of tion that is, until it is just at the oint of coming to rest in its normal position.

The starting of a line finder to find and complete connection with the calling line is effected through the medium of aconductor 29 which is under the control of the relay 22 of the group of starting apparatus E, 00111 mon' to the groups A and B. When relay 22 is energized asa result of the energiz'ation of relay 24, it closes in its tron-t contact 25 a path to ground for the starting. conductor 29 by way of the resting-contact 26 of relay 23. v The grounding of the conductor 29 energizes themotor magnet of the'sequence switch 200 or one of the finder circuits that has been preselected and is standing inreadiness to take a call. 7

As many finder circuits may be provided as are necessary to handle the callsfrom' the associated groups of subscribers lines. In the present instance two finder circuits, the first and lastof the series, are shown complete with respect to the elements involved in the operation here to be described, while such partsof a circuit intermediate in the series are illustrated as serve to show the relation of this circuit with its associated circuits. h v

The manner of effecting the preselection of the finder circuit to place it in readiness to respond tova. calling line will be described hereinafter. For the present it will be suiiicient to assume that the finder circuit C' which terminates in the finder switch C is, the circuit that has been preselected and is- "stan'ding' in readiness to take the next call.

naemvo The preselected condition is one in which the sequence switch 200 of the finder circuit is standing in its second position. This being the case, the rounding of the starting conductor 29 by the operation of the relay 22, completes a path for the energization of relay 30 of finder circuit C by way of the left-hand winding of that relay, sequence switch contacts 206 closed in the second position, starting conductor 29, front contacts 25 of relay 22, and resting contacts 26 of relay 23. Relay 30 in operating closes in its front contact 31 an energizing circuit for the motor magnet of sequence switch 200 by way of sequence switch contacts 202 and 208 closed in position 2. The sequence switch thereupon moves out 01 position 2, and when it reaches position 3 completes a circuit for the flow of current through the up-drive magnet 32 of the line finder by way of conductor 20, contacts 207 of the sequence switch, closed in position'3, front contacts 31 of the relay 30, and contacts 208 closed in positions 18 to 14: and 2 to 7 of sequence switch 200 to ground. The consequent energization of up-drive magnet 32 of finder switch C causes it to force the elevating bar of the brush carrying rod into engagement with the associated driving disk, and as a re sult the brush car "ier starts to move up.

Each of the trip magnets 16, 17, etc., is adapted in operating to cause a partial rotation of its associated trip rod 81, that moves all the tripping yokes 82 mounted on the rod into position to engage and operate the corresponding tripping levers, controlling corresponding sets of brushes upon all of the finder switches. As it is assumed in the present case that station A. is calling and that the trip magnet 16 of group A is operated, as soon as line finder C starts to move up, the set of brushes corresponding to group A is tripped and made operative. Immediately following this in the upward movement of the switch, commutator'segment K is engaged by the cooperating grounded brush, and a circuit is closed that releases the trip magnet 16 and opens the starting circuit. The circuit thus closed extends from ground at the K segment of the line finder commutator, by way of sequence switch contacts 209, conductor 83, through the windings of relays 23 and 33 in parallel to battery 13. When the contacts 35 of the relay 33 are closed in the actuation of that relay, the circuit is completed for the energization of the motor magnet of the sequence switch 200 of finder circuit C by way of contact 203 closed in position 3 of the switch. This moves the switch from its third to its fourth position. Relay 23 in operating opens its contact 26, thus breaking the path to ground of the conductor 58 that theretot'ore had been maintaining the'trip magnet 16, the group relay 24 and the starting relay 22, energized.

The opening of conductor 58 by the operation of relay 23 not only releases the trip magnet 16 and the group and starting relays, but also prevents the reenergization of the starting relay and 01 the trip magnet and group relay of any of the groups as long as relay 23 remains actuated. The duration of operation of relay 23 is controlled by a locking circuit which relay 23 closes for itself when it is actuated. This locking circuit is closed in contact 34 of the relay 23, and extends serially through the sequence switch contacts 210 of the sequence switches 200 of all the finder circuits to ground. The sequence switch contacts 210 are closed in positions 23 to 1; therefore the locking circuit is completed in the contacts 210 in position 1 in the case of all the finder circuits that are idle or normal, and is closed in the contacts 210 in positions 2%; and be yond in all of the finder circuits that have been selected and are in use. Consequently the relay 23 and 33 are kept energized by this locking circuit until the sequence switch 200 of one of the finder circuits is moved into its 2 or waiting position to open the locking circuit. This movement of the sequence switch of the next idle finder circuit in order, is the act of preselection, and is effected through the medium of a circuit closed by the relay 33 when that relay is energized by the closure of the sequence switch contacts 209 of the finder circuit that has just taken the call. In operating, relay 33 closes its contacts 35 and 36. The closure of contact 35, as previously stated, causes sequence switch 200 to move its contact out of the third and into the fourth position. The closure of contact 36 completes a circuit that extends by way of sequence switch contacts 211 of the finder circuit C before it has moved out of the third position and in series throu h such of the sequence switch contacts 211 or other finder circuits as may be busy, and consequently have their sequence switch contacts in positions 4 to 17, to the contacts 211 of the first finder circuit that has its sequence switch in its normal or first position, at which point the circuit is completed through the motor magnet ot. that sequence switch 200 to battery by way of sequence switch contacts 203 in their first position. Assuming that this is the sequence switch of finder circuit D, the switch moves its contacts 210 into the second or waiting position of the switch, thus opening them and breaking the looking or holding circuit previously traced for the relays 23 and Relay 23 in releasing closes its normal contacts 26, thus again establishing the connection to ground of conductor 58. In this manner the placing of another finder circuit in readiness to receive a call makes the starting relay 22 and the group relays 24 and trip magnets 16, 17, etc. of the various groups again responsive to the initiation of a call.

As previously explained, the circuit of the magnet 32 of the line finder G is closed to start the upward movement of the line finder brushes when the sequence switch of finder circuit C reaches its third position. This upward movement continues until the finder switch finds the line that has initiated the call. lVhen the brushes of the line finder encounter the terminals of the calling line, a; circuit is completed for the energization of the relay 37 of the finder circuit by way of the conductors 38 and 39 of the calling, line, joined at the sub-station A in the telephone switch hook contacts, conductors 48 and 49 of the finder circuit, connected with line conductors 38 and 39 through the medium of finder brushes 40 and 41 and finder terminals 44 and 45 respectively, sequence switch contacts 213 and 214 closed in positions 2 to 4 of. the switch, and the contacts of relay 52. This last mentioned relay 52 is connected byway of sequence switch contacts 212 closed in positions 2 to 4 and conductor 50 to brush 4201f the line finder, and finds a circuit to ground for its energization whenever the brush 42 engages a terminal 46 of a line that is not in use for service either as a calling or as a called line, the path to ground being by way of the winding of the cut-off relay llof the tested line. If a line is in service either as a calling or as a called line, the third conductor 53 of the line has a connection from battery by way of a resistance, such as the resistance coil 64 of the finder circuit, that is relatively low in value as compared with the resistance of the relay 52; and therefore when the relay 52 is brought into connection with the conductor 53 of such a line, it is shunted and does not operate to connect the relay 37' with the talking conductors of the line. Therefore as the brushes are moved over the terminals of the line finder, the circuit of .the test relay 37 is completed to the line conductors of such lines as are not in service; and when a line not in service is found with its telephone off the hook and its circuit therefore complete at the substation, as calling substation A, the relay 37 is energized and opens its contacts 54.

The above described arrangement for identifying a calling line by means of a double test made upon each line engaged by the finder switch is not claimed herein, but is one of the features described and claimed in the co-pending application of S. B. lVilliams, Jr., Serial No. 858,461, filed August 25, 1914. I

After the relay 30 of the finder circuit was initially energized over the path by way earn-7o;

of. the sequence switch contacts 206, closed in the second position'of the switch, and the contacts 25 of starting relay 22, it was maintained energized by a path extending from ground through the normally closed contacts 54 of the test relay 37, front contacts 55 of relay 30,. sequence switch contacts 216 closed in positions 2 to 4, the righthand Windin of relay 30, sequence switch contact 217 c osed in positions 2' to 9 and a resistance coil 56 to battery. Therefore when the test relay 37 is energized and opens its contacts 54 included in this locking circuit, the relay 30 is deenergized and permits the retraction of its armatures. Armature 31 of relay 30 in opening its front contact interrupts the energizing circuit for the upedrive magnet 32 by way of sequence switch contact 207 and conductor 20; and in 7 closing its normal or resting contact, it completes a circuit for the energization of the motor magnet of the sequence switch 200 by way of sequence switch contacts 202 closed in positions 3 to 4, normal contact 31 of relay 30, and sequence switch contacts 208 closed in positions 18 to 14 and 2 to 7 of the switch, to ground. Thus the finding of the calling line stops the brushes of thefinder switch upon the terminals of that line, and causes'the finder sequence switch 200 to move its contacts out of the fourth position.

In moving out of position 4, the sequence switch of the finder circuit closes, in its contacts 212 in the 4% to 12:} positions, a circuit for the energization of the cut-off relay 11 of the calling line, this circuit including the resistance coil 64. and being completed by way of brush 42 and terminal 46 of the line finder switchand the third or local conductor 53 of the calling line. Cutofi relay 11 acts to disconnect line relay 12, and the latter relay releases its armature to remove the ground from the conductor 18 common to the group of lines in which the calling line is located, and thus alter the 7 starting condition of the line.

As the starting condition of the calling line persists up to the moment the calling' line is found and its line relay 12 released, and as a second finder switch is put in readiness and made responsive to the starting circuit at an early stage in the movement of the finder switch that is hunting for the calling line, provision is made for depriving the calling line and its associated group of lines of control over the starting circuit while the calling line is being hunted, and for restoring this control after the calling line is found. This is effected through the agency of the timing sequence switch 100 that is associated with each of the line groups. This sequence switch 100, as heretofore described, is started in the operation of the associated group relay 24 with the starting and group tripping circuit by the closure of sequence switch contact 103 when timing sequence switch 100 returns to its normal position. Thus after a finder switch has been made operative to find a calling line, the calling line and its associated'lines are not only deprived of control over the starting and tripping circuits for an interval long enough-to permit the calling line to be connected with, no matter where it may be located in the group; but also at the expiration of this interval the group of lines has its control over the starting circuit restored independently of whether the calling line is found or not, so that a failure tofind the calling line for any reason does not operate to deprive the lines in the group of access to the finder switch controlling circuits.

This provision of a timing switch for governing the control of the associated group of lines over the starting and tripping circuit, prevents the possibility of a single call making operative more than a single finder switch, and also cooperates in establishing such a relationship between the various groups of lines and the line finder controlling apparatus serving these groups in common, that none of the groups has undue preference in securing the services of finder switches. The relationship between the finder controlling apparatus and the lines of the various groups that brings about this result and that prevents the tripping oi more than a single set of brushes on a. finder switch, may be made clear by assum ing that the four stations A, A B and B call simultaneously. Under these circumstances the line relays 12 of all four lines are simultaneously energized and attract their armatures to apply grounds to the conductors 18 of the two groups A and B. The grounding of the conductor 18 of each, of the groups, completes the circuit of and energizes the relay 19 of that group. These relays simultaneously close their contacts 21 to connect the right-hand winding of the associated group relay 24 with the starting relay test conductor 57. But the relay 19 of the A group in attracting its armature, opens the circuit of the test conductor 57 to the B group and the groups beyond. The consequence is that while the energizing circuit relay 24 of the A group is completed by way of the test conductor 57 to ground by way of the contacts 26 of relay 230i the starting group, the energizing circuit of relay 2%: of the B group, although closed in the contacts of relay 19 of that group, is open in the back contact 21 of the relay 19 of the A. group. Therefore the relay 2% ot the A group is operated and relay er of the B group is not.

Relay 2% of the A group in operating starts the rotation of associated sequence switch 100, opens the conductor 58 to the groups beyond the A group, and closes, in its contacts 27, the energizing circuit over the conductor 58 in which circuit are included the starting relay "22, the trip magnet 16 of the associated group and the locking winding 01 the relay 21. The relay in operating closes the starting wire 29 and starts the preselected and waiting line finder. The started finder switch, in grounding commutator segment K atthe end of the group-selecting stage of its movement, operates the relays 23 and 33 of the starting group E, the relay 23 opening the energizing circuit of the starting relay 22 and the trip magnet 16, and the relay 33 closmg circuits that preselect the next idle finder circuit and move the sequence switch of the appropriated finder circuit from its third to its four position. The preselection ot the idle finder circuit opens the locking circuit of the relays 23 and 33, and the relay 23 in releasing restores the circuit of the starting relay 22 to a responsive condition.

At this moment the elevator of the line finder of the first finder circuit is moving up to bring its tripped brushes into connection with the terminal of the first encountered calling line in the corresponding group A, and the starting relay 22 has just been rendered available again by the re lease of relay 23. The relay 19 of the A group is inert, having been deenergized when the sequence switch 100 of that group starts to rotate and opens its contacts 103 an instant after the call comes in, and the relay 24 is inert, having been deenergized when relay 23 operated to open its contacts )6. Conductors 57 and 58 are therefore closed through to the B group.

As stations B and B of the B group are both assumed to be calling, the relay 19 of that group is energized and the initial energizing circuit by way of test conductor 57 is closed through to the right-hand winding of relay 24E of the B group. Consequently as soon as the contacts 26 of relay 23 are closed by the release of that relay, relay 2-1 of the B group is energized, closes its front contacts 27 and completes the energizing circuit for operating the trip magnet 17 associated with the B group, holding the relay 24 of that group energized, and ener- 'gizing the starting relay 22. This last mentioned relay immediately operates, in the manner already described, to open the 1m- "tial energizing circuit forall the group re- 'is again rendered available to the calling lines.

\Vhe'n the relay 21 of the B group operated, it started the rotation of the se- (juence switch 100 of that group, thus opening the conductor 18 oftheB group in sequence switch contacts 103. The conductors 18 of both theAand B "groups are therefore open in their contacts 103, awaiting the closure of these contacts upon the coinplaice of rotation and return to normal of their respectivesequence switches 100. As the sequence switch ofthe A group was the jfirst to start its rotation, it will be thefirst, "assuming the rate of rotation of both switchest'o be the'jsanie,to return to normal and close its contacts 103.

As soon as sequence switch contacts 103 of'the A group are again closed, the assopiate'd relay 19 is energized byway of the ground applied to conductor 18 by the line relay 12 of the waiting calling line A the line from station A"having been found and its "line relay'released before "the sequence switch contacts 'arecl'ose'd. As thestai'ting circuit was rendered available by the starting of'the second finder circuit and the preselection of the third finder circuit, the start- "ing'relay 22 is therefore again energized'to start thelinefinder of the third finder ciredit and pre'select the fourth finder circuit, 45:

in the manner already described. As it is jthe'operation of the relay 2st of the A'group "that energizes the starting circuit and starts "the upward movement of the third line finder, it is the trip magnet 10 of the A group that is energized in this case, and the corresponding set ofs'witch brushes of the third line'finder that is tripped and made operative, 1

YVhen the'third line finder has been started and the fourth line finder preselected and 'put'in' readiness, the starting circuit is again rendered available. Therefore as soon ""as' the sequence switch 100 of the B group returns to normal and closes its contacts 103, the relay 19 of the B group is energized over "theground path supplied by, the

1 line 1'el'ay12 of'theiline to'station B the line from station B hayingbeen connected with before contacts 103"are"c1osed. The

result is that relay trip magnet 1'7 associated with the B group of lines, and starting relay 22 are allenergized, the relay 22 acting to'start the line finder ofthe'p'rese- V lected fourth finder circuit, and the trip magnet 17 acting to trip and make operative thebrushes that pass over theterminals of the B group of lines. 0

From the foregoing it may be seen that I V served. -;Thus in the case assumed above,

station A in the A group first-has its connection extended, then station E "in the 'B group, then station A in the A group,

then stationIB in the B group The control which the lines of each group haveover the associated group tripping or selecting circuit and the common starting circuit, is governed by group apparatus whichacts in the manner described to limit the frequency with which the lines of the group may start and selectively operate the finder switchesto a rate less frequent than the rate at which the common startlng circuit operates to start a waitingfinder switch "and place in reachness another finder switch. 7

i It may also be seen that the organization of the .system .is such that when calls occur group at a time is given control of thegroup selecting mechanlsin of a started finder switch, so that the tripping and making operative of two setsof brushes on a finder switch, and the consequent connection of the findercircuit with aline in each of the calling groups, is prevented. 7

The apparatus also acts in the manner already described to render-the starting and ,group selecting circuit unavailable to the hues of a particular group after the circuit has taken a call from that groupfor a length of time greater thanthe timerequir'e'd for the finder switch to move into engagement with the terminals of'the calling lineand alter the calling condition of the lineorcallin-g relay 12, inthis way preventinga single call from starting more than one finder switch,

As'the invention herein presented isnot concerned with the'particular manner in which the connectlon of the calling line,

after it has once been extended to a finder ;C1I(111t, 1s furthenextended and completed to "the line of a calling subscriben'it is not thought necessary that this part of'the'orsimultaneously indifi'erent groups only one nae-1,770

ganization be particularly illustrated or described. The conductors of the finder circuit may be extended to the calling line through the medium of a connecting cord terminating in a plug that is adapted to be inserted in a spring jack of the called line; or may be extended by means of antomatic selecting and connecting switches in any one of a number of ways that are well known and do not require description. In either case, it is to be assumed that the organization may be provided with such ordinary equipment as will enable the operator to receive the instructions from the calling subscriber, and control the apparatus involved in the completion of the connection.

In the specific embodiment of the invention here shown, it may be assumed that after the sequence switch 200 of the finder circuit has reached position 6, as a result of the finding of the calling line, it is moved out of that position and into the talking position l i by a circuit established in the process of extending the connection. In the talking position 14 of sequence switch 200, the tall:- ing conductors 48 and 49 are extended through to the apparatus with which the right-hand end of the finder circuit is assumed to be provided, by way of sequence switch contacts 213 and 214:, closed in position 14 of the switch; the third or local conductor of the finder circuit is extended through, in this position of the sequence switch, by way of contacts 212 and 217 of the switch,-this conductor receiving current for holding the relay 30 of the finder circuit and the cut-ofii relay 11 of the calling line energized; and the fourth conductor with which the finder circuit is shown to be provided, and which may have a special use at this stage of the operation, is closed through by way of sequence switch contacts 207 and 208, and the closed contacts 31 of relay 30.

Furthermore, the arrangement may be such that at the end of the conversation, the flow of energizing current for the relay 30, by way of the third conductor of the finder circuit will be interrupted, thus permitting the closure of the back contact 55 of that relay, and the completion of a path for the fiow of current through the motor magnet of the sequence switch 200 by way of contacts 202, closed in the fourteenth position, and the back contact 54 of relay 37. When the sequence switch moves to position 16, it closes in its contacts 208 a path from ground for the energization of the downdrive magnet 62 of the finder switch, thus quence switch contacts 218, closed in position 16, and commutator segment Y of the finder switch.

lVhile the particular embodiment of the invention disclosed, employs a sequence switch for making the calling line inefiective during the period of selection, it will be understood that other well-known types of delayed-action switches or switch con trolling arrangements may be substituted for performing this function without do parting from the spirit of the invention.

What is claimed is:

1. The combination with a plurality of telephone lines arranged in groups, oi a group relay for each groupv adapted to be operated when any line of the corresponding group calls, group selecting means under the control of said group relays, a switch for each group adapted to be operated by any of the lines of that group in calling, and a commoninitial energizing circuit for said relays extending serially through resting contacts of said group switches and adapted when the switch of any group is operated to be connected with the relay of that group and to be disconnected from the switches of other groups beyond in the series.

2. The combination with a plurality of telephone lines arranged in groups, of a switch for each group operated by any line of the corresponding group in calling, a relay for each group having a holding winding and an initial energizing winding, group selecting means controlled by said relay, a relay common to said groups having an. energizing circuit extending serially through resting contacts of said group relays, said energizing circuit being adapted to be completed through the holding winding of any of said group relays that is operated and at the same time to be cut off from the relays of the groups beyond, and a common initial energizing circuit extending through resting contacts of said common relay and serially through resting contacts of the switches of the various groups, said circuit being adapted when any of said group switches is operated to be completed through the initial energizing winding of the corresponding group relay and at the same time to be cut off from the switches of the groups beyond.

3. The combination with a plurality of telephone lines arranged in groups, of a finder switch adapted for group and individual line selection, a group relay for each group having an initial energizing winding and a holding winding, each of said group relays being adapted in its operation to control the group selecting operation of said finder switch, means under the control of any line of each group in calling for momentarily closing a circuit through the initial energizing winding of the corresponding group relay, an energizing circuit adapt ed to be completed through the holding winding of any one of said group relays in the operation thereof, and means operated at the end of the group selecting operation of said finder switch for-rendering ineii'ective said holding circuit.

4. The combination with a pluralityot lines, of a plurality of finder switches for making connection therewith, a starting circuit adapted upon successive energizations to start successive finder switches, means under the control'of any of said lines for efi'ecting the energization of said starting circuit, and means controlled in the energization of said starting circuit for rendering said first mentioned means temporarily ineffective to reenergize' said starting circuit.

5. The combination with a plurality of lines, of a plurality of finder switches for making connection therewith, a starting circuit adapted upon successive energizations to start successive finder switches, line-controlled means for eii'ecting the energization of said starting circuit, and a timing switch .for rendering said line-controlled means temporarily inefiective to reenergize said starting circuit, said timing switch being under the joint control of said line-controlled means and said starting circuit.

6. The combination with a plurality of 7 lines, of a plurality of finder switches for making connection therewith, a starting circuit adapted upon successive energizations to start successive finder switches, line-controlled means for effecting the energization of said starting circuit in the initiation of a call, and a timing switch actuated in the energization of said starting circuit for depriving the calling line of control over the starting circuit for a constant predetermined interval.

7.- The combination with a plurality of lines divided into groups, of a plurality of finder switches adapted to be started successively by the initiation of calls by said lines, means associated with each group of lines and actuated by the initiation of a call in the corresponding group to cause a started finder switch to come into operative relation with the lines of that group, and a timing switch for each group for rendering said means again operative only at the expiration of a predetermined time interval after a previous actuation.

8. The combination with a plurality of lines divided into groups, of finder switches for making connection therewith, group selecting means for each group of lines adapted when operated to bring a finder switch into operative relation with the lines of the corresponding group, and a timing switch for preventing said group selecting means from being again operated until the expiration of an interval greater than that re quired for a finder switch to traverse all of the lines of the group.

9. The combination with a group of tele phone lines, of a plurality of finder switches for making connection therewith, a starting circuit adapted upon successive energiza tions to start successive finder switches, means operated by any line in calling to energize sald starting circuit," and a timmg switch governing the control of the lines of said group over said starting circuit,- said switch acting when said line-operated means energizes said starting circuit to deprive the lines of the group of control over said starting circuit, and acting to restore said control at the expiration of a constant predetermined interval greater than that required for said-finder switch to traverse all the lines ing to cause the closure of said circuit, a finder switch adaptedto be started by the closure of sald starting circuit, means operated in the starting of said finder switch for opening said starting circuit and placing a second finder switch in operative relation with said circuit, and means made operativein the placing of said second finder switch in operative relation with said starting circuit for restoring said circuitto the control of the other telephone lines.

12. The combination with a plurality of telephone lines, of a starting circuit under the control of said lines and adapted to be made operative by anyline in calling, a finder switch normally in operative relation with said starting circuit and adapted to be started when said starting circuit is closed, a locking relay operated in the starting of said finder switch for opening said starting circuit and rendering the same irresponsive to the control of the associated telephone lines, a second finder switch adapted to be moved into operative relation with said starting circuit by the movement of said first finder switch, and switch contacts operated to release said locking relay when said second finder switch comes into operative relation with said starting circuit.

18. The combination with a finder switch adapted for group and individual line-selection, of groups of lines extending to 7 starting circuit, of subscribers lines adapted in callgroups of stationary terminals on said switch, an electromagnetic group selection controlling device for each group of terminals, an energizing circuit for each device adapted to be closed upon the initiation of a call by any line in the corresponding group, means actuated in the closure of any group, energizing circuit for depriving lines a of other groups of control of their respective lines arranged in groups, of a plurality of finder switches therefor, startlng and group selecting means for said finder switches, means under the control of each of said lines in calling for energizing said starting means Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. 7

and the group selecting means corresponding with the group in which the calling line is located, and means for preventing the renergization of said starting and group selecting means, by any line in the same group until a finder switch has made connection with said calling line.

15. The combination with a plurality of lines divided into groups, of a plurality of finder switches adapted for group and individual line selection, a circuit adapted upon successive energization to effect the starting and group selection of successive finder switches, line-controlled means associated with each group for elfecting the energization of said circuit, and means adapted to render the line-controlled means of each group ineffective for an interval after it has operated to energize said circuit.

In witness whereof, I hereunto subscribe my name this 27th day of January, A. D.

SAMUEL B. WILLIAMS, JR.

Washington, D. G. 

